That day, Kyojuro Rengoku arrived in Tokyo alongside his disciple, Mitsuri Kanroji.
According to reports gathered by the Demon Slayer Corps, a demon had been sighted within the city. Though not yet officially appointed as the Flame Hashira, Kyojuro had already begun undertaking missions of that level, guided by both his father's expectations and his own unwavering resolve.
Makijuro Rengoku had once told him something he would never forget:
"You don't wait until you are worthy of the title you wear it first, and grow into it."
Because of that, Kyojuro wore the flame-patterned haori with pride, embodying the spirit of the Flame Hashira long before formally inheriting the position.
"Rengoku-san, are there really demons in a place like this?" Mitsuri asked, her wide eyes scanning the lively streets filled with lantern light, merchants, and laughter.
Kyojuro smiled brightly, his voice as confident as ever. "That is precisely what we are here to determine!"
He paused briefly, glancing toward the rows of food stalls lining the street.
"However… investigation requires proper energy! Shall we eat first?"
Mitsuri's face lit up instantly. "Yes, please!"
And so, what began as a brief stop turned into something far more… memorable.
Moments later, a resounding voice echoed through the street again and again:
"Delicious!"
"Delicious!"
"Delicious!"
The repetition was so enthusiastic, so utterly sincere, that passersby couldn't help but stare. Kyojuro, however, remained completely unfazed, savoring every bite with genuine appreciation.
If anything, it was the onlookers who grew uncomfortable under his unwavering confidence.
Mitsuri, for her part, saw absolutely nothing strange about it. Good food deserved to be praised was that not natural?
Time passed far quicker than expected.
By the time they finished…
The sun had already begun to set.
Mitsuri had consumed an astonishing amount of food enough to empty several stalls entirely yet her figure remained unchanged, her expression content and cheerful as ever.
The surrounding crowd could only watch in stunned silence.
With their energy fully restored, the two finally separated to investigate the area more efficiently.
Mitsuri wandered into a quiet alleyway, the lively sounds of the street fading behind her. Just as she turned to leave, a small kitten appeared, mewling softly as it brushed against her leg.
Her heart melted instantly.
"Oh my, you're adorable…"
She bent down, gently picking it up and cradling it in her arms, completely lowering her guard.
Far above, concealed in the shadows of a nearby building, a figure took aim.
A rifle cold, precise, and utterly out of place in a traditional battlefield was trained directly on her.
But before the trigger could be pulled
A sharp metallic crack echoed through the air.
The assailant's eyes widened as he spun around.
Too late.
A blazing figure surged upward from below, his presence like a roaring flame.
Flame Breathing, First Form: Unknowing Fire!
Kyojuro's blade flashed, cleaving cleanly through the rifle before it could fire. The weapon split in two, falling uselessly to the ground.
The demon staggered back, shock flashing across his face.
Kyojuro studied him carefully, his expression sharpening.
This was no ordinary demon.
The markings in his eyes confirmed it
Lower Rank Two of the Twelve Kizuki.
The demon let out a bitter laugh, his gaze filled with resentment. "So… the Flame Hashira again…"
Kyojuro did not recognize him, but the hostility was unmistakable.
Years ago, when he was still weak, this demon had encountered Makijuro Rengoku and barely escaped with his life. That encounter had left behind not just scars, but an obsession.
Driven by fear and humiliation, he had clawed his way upward, gaining strength through desperation until he reached the rank of Lower Moon Two.
And now
He sought revenge.
Flame Breathing, Second Form: Rising Scorching Sun!
Kyojuro moved instantly, his blade carving a powerful upward arc. The strike landed cleanly, tearing open the demon's chest and sending blood spraying outward.
Yet the demon did not retreat.
Instead, he smiled.
His shadow twisted unnaturally, spreading across the ground before rising upward like a living entity. From within it, multiple gun barrels emerged, forming a grotesque fusion of flesh and weaponry.
His Blood Demon Art.
A barrage erupted at point-blank range.
Gunfire roared through the alley, bullets tearing through the air with deadly precision. Kyojuro reacted instantly, his movements sharp and controlled as he deflected and evaded as many shots as possible, though several grazed his body, drawing blood.
Then
Explosions.
Hidden charges detonated in rapid succession, flames and debris engulfing the area.
At the same moment, Mitsuri sensed the disturbance.
She turned instinctively, drawing her Nichirin Blade but before she could move, shadows pooled beneath her feet.
They rose, taking the form of feral wolves.
She froze for a split second
And that was enough.
The shadow beasts lunged simultaneously, their jaws snapping shut. One clamped onto her blade, another darted toward her flank.
Mitsuri panicked briefly, her inexperience showing.
Yet
Even so
Her body moved.
Instinct.
Strength.
Her arm shot forward, grabbing one of the shadow wolves by the throat mid-lunge. With her other hand, she seized another, lifting it effortlessly despite its violent struggle.
Her expression shifted, determination replacing hesitation.
"You shouldn't attack people like that…"
Her grip tightened.
The shadow constructs shattered instantly, dissolving into nothingness.
Back atop the building, the demon smirked through the smoke and fire.
"You brought a partner, didn't you?" he taunted. "Someone who can't even properly wield a blade?"
Kyojuro stood firm despite his wounds, his stance unwavering.
"Mitsuri is strong," he said confidently.
The demon scoffed. "Strong? She couldn't even defend her weapon "
Kyojuro's eyes burned brighter.
"I believe in her."
And then
He moved.
The flames surged around him, his presence overwhelming, suffocating.
The demon's confidence shattered instantly.
That same pressure.
That same fear.
It hadn't disappeared
It had only grown stronger.
In desperation, the demon threw down a smoke bomb, attempting to obscure his escape.
But before it even hit the ground
Kyojuro was already there.
Flame Breathing, Ninth Form: Rengoku!
A devastating, singular strike.
Clean.
Unavoidable.
The demon's head separated from his body in an instant.
As his consciousness faded, fragments of his human past surfaced training with fellow disciples, laughing, striving, believing in a code he had long abandoned.
A hand reached out to him in memory.
He hesitated
Then accepted it.
And vanished.
With the battle concluded, the remaining traces of the demon's Blood Demon Art dissipated entirely.
Mitsuri approached, unharmed, her expression relieved.
Soon after, members of the Kakushi arrived to handle the aftermath.
This mission marked a turning point.
Not long after, Kyojuro Rengoku was formally appointed as the Flame Hashira, succeeding his father and carrying the title forward with unwavering conviction.
Mitsuri Kanroji continued to train under him as his Tsuguko, inheriting not only his techniques but also his spirit.
Upon returning home, Kyojuro reported everything to Makijuro.
For a moment, his father said nothing.
Then, quietly, he reached out and ruffled Kyojuro's hair.
"Well done."
It was simple.
But it carried weight.
Senjuro beamed with pride, his admiration for his older brother evident despite knowing he himself lacked the talent for the sword.
That evening passed peacefully
Until a familiar presence appeared beyond the threshold.
A voice, calm yet unmistakable, broke the stillness.
"…It seems something significant has occurred."
Kokushibo had arrived.